Liquid-dispensing apparatus



March 25, 1930. J, g, Dgws v 1,752,068

I LIQUID DISPENSING APPARATUS Fil'ed Feb. 16, 1929 4 Sheets-Sheet l LIQUID DISPENSING APPARATUS March 25, 1930.

4 Sheets-Sheet 3 Filed Feb. 16, 1929 L /Z6 4! v 6 t i 97 INVENTOR. Z 7/ Z! By 7 QM/ ATTORNEYS.

March 25, 1930;

J. B. DAVI Filed Feb, 16, 1929 I LIQUID DISPENSING APPARATUS 4 Sheets-Sheet 4 w //i w W INVENTOR.

BY Z

ATTORNEYS.

Patented Mar. 25, 1930 UNITED STATES PATENT OFFICE JOHN B. DAVIS, 01 SPRINGFIELD, MASSACHUSETTS, ASSIGNOR TO GILBERT & BARKER MANUFACTURING COMPANY, OF WEST SPRINGFIELD, MASSACHUSETTS, A COB- IPORATION OF MASSACHUSETTS LIQUID-DISPENSING APPARATUS Application filed February 16, 1929. Serial No. 340,395.

liquid as its cylinder is being filled. The two pistons are interconnected so that as one is raised the other is lowered and the movement of the pistons is utilized to control the operation of valve means, which controls the supply to and the discharge from the measuring cylinders. The arrangement is such that one cylinder fills while the other discharges and liquid is positively expelled from the discharging cylinder by its piston, which is forced downwardly due to its connection with the then rising piston in the other cylinder.

A dispensing apparatus of this type is disclosed in my copending application for U. S. Letters Patent, filed January 2, 1929, under Serial No. 329,743, and this invention is an improvement on that disclosed in said application.

The main object of this invention is to provide improved mechanism for interconnecting the two pistons of the measuring cylinders and enabling independent adjustment of the strokes of such pistons.

Other objects and advantages will appear from the following description and will be pointed out in the appended claims. 1

The invention will be disclosed with reference to the accompanying drawings, in which Figs. 1 and 2 are exterior front and side elevational views of a dispensing apparatus embodying the invention;

Fig. 3 is a sectional elevational view drawn to a larger scale and taken on the line 33 of Fig. 2;

Figs. 4 and 5 are fragmentary cross sectional views, drawn to a still larger scale and taken on the lines 4-4 and 55, respectively, of Fig. 1;

Fig. 6 is a view taken on the line 6--6 of Fig. 5;

Fig. 7 is a detail view of the main valve body showing its passages and ports;

Fig. 8 is a sectional view of the valve which cooperates with said body;

Fig. 9 is a sectional view showing one of the pistons in its measuring cylinder;

F g. 10 is a sectional plan view taken on the line 1010 of Fig. 9;

Fig. 11 is a sectional plan view taken on the line 1111 of Fig. 6;

Fig. 12 is a fragmentary cross sectional View illustrative of the construction at the upper ends of the measuring cylinders; and

Fig. 13 is a sectional plan view taken on the line 1313 of Fig. 5.

The dispensing apparatus includes two upstanding transparent measuring cylinders 20 (Figs. 1 and 3) which are mounted side by side on a common base member 21. The latter is supported by four pipe columns 22 (Figs. 5 and 6) from a ring 23 and this member is supported by three pipe columns 24 (Figs. 3 and 4) from a base 25. The space between ring 23 and base 25 is enclosed by a two part casing 26 of circular cross section, suita ly secured to circular flanges 27 and 28 (Fig. 4) on ring 23 and base 25, respectively. The space between members 21 and 23 is also enclosed by a two part casing 29 (Figs. 5, 6 and 13) of square cross section, suitably secured to member 21. The lower end of casing 29 is closed by a flanged head 30, secured thereto as indicated. Slidable on casing 29 is a canopy 32 which telescopes over the flanged upper end 31 of ring 23 and closes such end, the canopy and flange 31 being suitably secured as indicated in Fig. 5. The lower ends of columns 22 slide into holes in lugs 33, formed on and projecting inwardly from ring 23, and are held in position by the nuts 34 and by set screws 35. The casing 26 has. suitable doors 36 and 37 (Fig. 1) therein,the formerallowing access to the operating handle of the pump and the latter allowing access for connectingthe pump to the underground suppl tank (not shown). On casing 29 is a suita 1e register 38. The dispensing hose 39 is attached to member 21 hp a fitting 40, preferably having a sight g ass 41 therein. The measuring cylinders metrically across the same is a cross bar 47,

the ends of which rest on ring 44 (Fig. 12). A'pair of studs 48 extend one through each end of cross bar'47 and through ring 44 to base 21, into which they are threaded. Long, hexagonal nuts 49 are threaded on the upper ends of studs 48 and serve to clamp the cross bar 47 to ring 44 and the cylinder between the latter and base 21. The dome 42 rests on the upper ends of nuts 49 and is secured thereto by cap screws 50. Threaded centrally through cross bar 47 is a screw 52 which extends throughdisc 45 (see Fig. 3) and depends into the upper end of the underlying measuring cylinder, forming an adjustable abutment. The upper ends of both cylinders 20 are interconnected by piping 53, secured as indicated to discs 45 and having a central passage 54, preferably screened as at 55, opening to the atmosphere.

As shown in Fig. 3, within each cylinder 20 is a piston. Each such piston comprises a body 56 (Figs. 9 and 10) which is circumferentially grooved to receive a spring 57. This spring is made up from a suitable length of close wound coil spring, the ends of which are brought together and suitably joined, thereby forming an annulus'of appropriate inside diameter to fit in the aforesaid groove. Surrounding spring 57 is the cylindrical part of a cupped piston leather 58. The flat annular part of the leather rests upon the upper face of body 56 and the latter has a central upstanding cylindrical part 59 which passes upwardly through the opening in the leather. An annular ring 60 encomp sses part 59, rests on top of the flat annular part of the piston leather and is secured to body 56 by screws 61 (Figs. 9 and 10). The spring 57 which is compressed to some extent when the piston is inserted in the cylinder, presses radially outward at many points on the cylindrical part of the piston leather 58 and tends to hold the same in close contact with the walls of the glass cylinder. Pressure of liquid beneath the piston also serves the same purpose. The construction is calculated to maintain a fluid tight joint between the piston and the glass'cylinder, notwithstanding that the latter may be somewhat irregular and not exactly circular in form. The space within spring 57 is stuffed with packing 62 in order to exclude the volume of liquid which might otherwise enter this space and. under certain conditions, cause a discrepancy in measurement as will later appear.

The piston body 56 has in its lower face a central cylindrical recess 63 and leading upwardly therefrom through the body are three holes 64, each formed in a bushing held in body 56 by heading over its upper and lower ends. The recess 63 and holes 64 afford passages through the piston for the purpose of permitting the escape of air from below the piston and for the purpose of venting that portion of the cylinder which lies below the piston. The flanged lower ends of the several bushings 65 afford valve seats, adapted to be engagedbyafioat66asavalve. Thefloatvalve is mounted to slide freely on the piston rod 67.

The upper end of rod 67 is shouldered down to pass through body 56 and mounted thereon is a baffle plate 68 which overlies the upper ends of holes 64. A special nut 69 threaded on the upper end of rod 67 serves to clamp the baffle, 68 to the piston body and the latter to rod 67. Liquid raises the float and the latter eventually closes the air passages 64' after the air has been exhausted from the cylinder below body 56. The float, when in position to close holes 64, substantially fills the recess 63,there being just enough clearanceto allow the float to dro and open passages 64 when-the piston body 56 abuts member 21. The upper face of member 60 is inwardly inclined forming with the corresponding face of body 56 a saucer-like receptacle, whereby occasional drops of liquid, which may at times pass through the vents 64 as air is being expelled, will drain back through these vents when they are subsequently opened. The baffle 68 deflects any liquid which may pass through holes 64 and confines it to the saucer-like receptacle. The lower face of member 56 is made perfectly flat and, to avoid trapping air beneath the piston, a series of grooves 70 are provided in said lower face which facilitate the outflow of air. These grooves, which maybe increased in number if necessary or desired, radiate from recess 63. Each groove is very narrow (Fig. 10) and gradually increases in depth from a minimum at its outer end to a maximum at its inner end (Fig. 9).

The stroke of each piston 56 is positively limited,on thenpward stroke by the engagement of nut 69 with the lower end of the overlying stop screw 52 and on the downward stroke by the abutment of the flat lower face of the piston with the flat upper face of member 21, whereby all liquid between such faces is positively expelled from the cylinder, leaving only such small volumes of liquid as may occupy the spaces around spring 57, float 66 and in grooves 70. If the piston is allowed to dwell in its lower position, these small volumes of liquid, just referred to, will also drain out, because vent valve 66 will have missible tolerances of measurement.

Each cylinder 20 is closed at its lower end by member 21 except for a single passage 71 which serves both for the inflow and outflow of liquid (Fig. 3). These passages 71 are formed in part in member 21 and in part in a valve body 72, secured to member 21 by bolts 73 (Fig. 5). A supply passage 74 is formed in the valve body 72 and a discharge passage 75 is formed in part in said body and in part in member 21. As shown in Fig. 5, passage 7 5 leads upwardly from the valve body into member 21 and then turns forwardly and extends to the discharge fitting 40, above described. This passage is provided with the usual air vent-valve 76 to prevent siphoning of liquid from passage 75 below the level of weir 7 6'. The valve body and its valve are separately shown in Figs. 7 and 8 and the two are shown in working relation in Fig. 5. The valve seat is on the circular rear face of body 72 and the several passages 71, 74 and 75 terminate in ports 77, 78 and 7 9,- respectively, leading to such face. These ports are spaced ninety degrees apart with the cylinder ports 77 diametrically opposed and the inlet port 78 diametrically opposed to the outlet port 79. The valve seat comprises an outer annular portion 80, a central inner portion 81 and connecting webs 82, all of which are located in the same plane. The valve is a cup shaped element 83, having 'a central hub 84 and a pair of diametrically opposed connecting webs 85. The end faces of hub 84 and the peripheral part of cup 83 are in the same plane and contact with the parts 81 and 80, respectively, of the valve seat while the webs 85 contact with one or the other of a pair of diametrically opposed webs 82. Assume that the valve, as shown r in Fig. 8, is superposed on the valve body shown in Fig. 7 without any relative change in angular positions of the parts, liquid from passage 74 will pass through port 78 into the right hand half of cup 83 and thence through right hand port 77 into the right hand passage 71. At the same time, liquid from the left hand passage 71 can enter the left hand part of cup 83 through the left hand port 77 and pass out, by way of port 79, into discharge passage 75. Thus, one cylinder 20 can be filled while the other discharges. The valve, when positioned as described, permits the left hand cylinder 20 (as viewed in Fig. 3) to be filled and the right hand cylinder to be discharged (Figs. 3 and 7 are taken in opposite directions).' The valve 83 is in-' termittently movable, by mechanism to be later described, through an angle of ninety degrees back and forth between two positions of rest, one of which has been described. To reach the other position, the valve is turned counter-clockwise as viewed in Figs. 7 and 8, or clockwise as viewed in Figs. 3 and 6, through an angle of ninety degrees. The right hand cylinder will then be connected to inlet passage 74 and the left hand cylinder to discharge passage 75.

The valve 83 is fixed to a shaft 86 by a pin 87 (Figs. 5 and 8). This shaft is mounted to turn in valve body 72 and extends forwardly therethrough,a suitable stufling box being provided, as indicated in Fig. 5, to insure against escape of liquid. The forward in Fig. 5 and which is secured to the valve body by bolts 91. A screw 92, threaded into housing and held in adjusted position by a lock nut 93, has an inner hemispherical end which bears on the flange 89 of shaft 86 and serves to press the valve 83 against its seat.

This screw is located in a recess in housing 90 and is normally covered and concealed by a removable cap 94.

Liquid, such as gasoline, is supplied under a pressure to passage 74 by any suitable means. As shown in Figs. 3 and 4, liquid is drawn up through a pipe 95, adapted for connection to an underground supply tank, by a pump 96 and forced by the latter through a pipe 97 and a passage 98. The latter is formed in a casting 99, which is bolted to and depends from valve bod 72 and intothe lower end of which pipe 9 is threaded. Pipe 97 preferably includes a union 100, which permits disconnection of the upper and lower parts thereof, so that the upper part of the apparatus, including the measuring cylinders, casing 29 and the mechanism therein, can be lifted bodily off from the pedestal comprising base 25, casing 26 and ,ring 23. To do this, the screws which hold canopy 32 to ring 23 are removed; the canopy is slid upwardly on casing 29 to gain access to set screws 35 and these screws are loosened; after which the casing29 and attached parts may be lifted free from its support. To enable this to be done, the lower end of casing 29 and its end closure 30 are cut away, as at 101, so as to clear lugs 33 (see Fig. 13).

The pump 96 is supported on a frame 102, secured as indicated in Figs. 3 and 4 to the three pipe columns 24. Upstanding from frame 102 are pairs of oppositely disposed lugs 103, in each of which is a clamping screw 104, and the pump has a depending part 105,

. Fig. 4, in which it lies entirely within casing 26, to the position shown by full lines, in .which the lever extends in part outside the casing and in position to enable it to be swung back and forth (in a plane at right angles to that in which it swings on pivot 107) to operate the pump. Interposed in the pipe 97 is a suitable filter 110. A pipe 111 connects the suction. pipe 95 and discharge pipe 97 and affords a by-pass around pump 96. Interposed in this by-pass is a pressure relief valve 112, which normally closes the same but opens whenever the pressure of the pumped liquid exceeds the normalrange of operating pressures. For example,- should 25 pump 96 be operated while the valve (not shown) on the end of dispensing hose 39 is closed, the valve 112 will open and by-pass the li uid,avoiding damage such as breakage 0 the glass c linders 20.

It will be evi ent that, as liquid under pressure enters one cylinder, say the left hand one in Fig. 3, the piston therein will be raised. The two pistons are. interconnected:

so that the raising movement of either will I effect a lowering movement of the other and secure a more rapid discharge of liquid than could be obtained by gravity flow alone. Also, the valve 83 is operated by means controlledby the position of the pistons, as will later be described in detail, so that the valve is reversed in position whenever a piston abutment 69 engages the fixed abutment 52.

When a piston is at .the top of its stroke, itscylinder contains, between the lower face of t e piston and the upper face of member 21, some definite measured volume as for example, one gallon or five liters. Theoretically, the stroke of both pistons should be equal but as a practical matter these glass cylinders are seldom exactly uniform and it is necessary to provide means, such as the stop screws 52, that enable the stroke of one piston to vary from that of the other. It is also necessary to incorporate in the connections between the two piston rods, provisions that will permit the strokes of different lengths.

Each piston rod 67 extends downwardly through a suitable stufling box, as indicated in Fig. 3, into the casing 29. The lower ends of these rods enter into guiding tubes 113, which are fixed to laterally projecting arms 114 on frame 99 and depend from such arms into casing 26, where they terminate with closed lower ends. Since these rods must of 65 necessity extend into casing 26, the-interior of which is accessible when door 36 is opened to operate the pump, they are encased in tubes, to prevent access thereto and possible improper manipulation thereof. For sim ilar reasons the closure 30 is provided, making it diflicult to reach up into the interior of casing 29 through the door opening and gain access to other parts, now to be described, which are associated with the piston rod.

Fixed to each piston rod is a member having a forwardly projecting lug 116 and a rearwardly extending lug 117 (Fig. 5). From lug 116, there extends, in a direction forwardly and inwardly, a third lug 118,

hereinafter referred to as a latch releasing means. Each rear lug 117 is slidably engaged with a stationary guide rod 119 suitably secured at its lower end to one of the arms 114 and at its upper end to base member 21. Mounted to slide in lug 116 in a direction parallel to the axis of the piston rod is a rod 120 having a head 121 on its lower end adapted to abut the lower face of lug 116. Threaded, and therefore adjustable, on the upper end of rod 120 is a nut 122 and interposed between nut 122 and the upper face of lug 116 is a spring 123. Loosely encompassing spring 123 and resting .on the upper face 0 lug 116 is a sleeve 124, which serves to limit the degree of compression of spring 123 by abutment with nut 122.

vThe head 121 of the rod 116, associated with one piston rod 67, is connected to the head 121 of the rod 116, associated with the other piston rod, by a flexible member, such as a sprocket chain 125, which passes around the lower half of the periphery of a pulley 126,. mounted to turn on a stud 127 fixed to I frame 99.

This pulley, as shown in Fig-11, is made up of a central cylindrical body 128 and two somewhat larger circular side plates 129 riveted thereto, and affording between them a groove to receive the chain. A pin 130 (Fig.

6) is fixed to and projects radially outward may be firmly clamped in place by a bolt 133 which passes through both side plates 129 and a slot 134 in the shoe. When these bolts are loosened, each shoe 132 may be forced radially ,outward by turning a hexagonal head 135 formed on a screw 136 which is threaded into body 128. Each screw is locked in position by a cotter pin 137 (Fig. 11) which passes through the shoe and through an unthreaded cylindrical extension 138 of head 135, such extension being received in a hole in the inner end of its shoe. The side plates 129 have rectangular slots 139, which enable access to heads 135. The stroke of the pistons, which is fixed by its travel between abutments 21 and 52, is adjusted so that each piston will displace a definite unit volume. Then the shoes 132 are adjusted to cause, in effect, a lengthening or shortening of the chain 125, as required. The independent adjustability of these shoes enables the stroke of one piston to vary from that of the other. In Fig. 6, it will be clear that that length of chain between pin 130 and the right hand head 121 has been, in effect, shortened by one of the shoes 132 which as shown projects beyond the periphery of the body 128 of the pulley. It is important that the necessary adjustments of shoes 132, having once been made, should be preserved and the present arrangement has been carefully designed for this purpose. The shoes are not only firmly clamped by bolts 133 but they are also held to extensions 138 by cotter pins 137 and such pins prevent the screws 136 from turning.

Referring now, particularly to Fig. 6 and the operation of valve 83, this valve is operated with great rapidity by elastic means, which are placed under stress by the movement of the piston rods but which are not released for action until a piston has reached the end of its upward stroke. The valve operating lever 88 swings between two stops 139 (Fig. 6) formed on a cross bar 140 secured to the valve body 72 by cap screws 141. Lever 88 is normally held stationary against one or the other of these stops 139 by one or the other of a pair of latches 142 adapted to engage the outer end of the lever, as shown in Fig. 6. Each latch 142 is pivoted at 143 to an upstanding lug on crossbar 140 and its outer end rests upon the head 144 of a rod 145 mounted to slide vertically in a bearing 146 on said cross bar. A spring 147 connects the latchto bearing 146 and tends to maintain the latch in the position shown in connection with the right hand latch in Fig. 6, in which head 144 abuts the top of bearing 146. The lower end of each rod 145 carries an adjustable abutment 148 adapted to be engaged by the underlying one of the pair of abutments 118, heretofore described as carried one by each piston rod 67. As shown in Fig. 6, the abutments 118 and 148 have al ready engaged and latch 142 has been partially moved but not quite enough to release lever 88. By adjustment of parts, the latch reaches release position at the same moment that a piston is arrested by abutment of members 69 and 52.

The elastic means for moving lever 88 from one to the other of its two positions consists of a spring 149 which is coiled around a rod 150. The latter at one end has a forked head 151 (Fig.3) which is pivotally connected to a lever 152. The other end of rod 150 is slidable in an eye 153 swivelled to the valve lever 88. The spring acts between the eye 153 and head 151', tending to spread them apart. The lever 152 is mounted, at a point intermediate its ends, to turn on a stud 154, which projects forwardly from a hub 155 on a cross bar 156, secured to the valve body 72 by cap screws 157. The lower end of lever 152 has a slot 158. which receives a roll 159, mounted on the upper end of a lever 160. This lever 160 is fixed to the squared front end of a shaft 161 (Figs. 5 and 6), which is mounted in a bracket 162, formed integrally with frame 99. The lower end of lever 160 is formed with two diverging arms 163 (Fig. 6) which are offset rearwardly (Fig. 5) so as to lie in the path of a hub 164 which projects forwardly from bracket 162. The lever 160 is limited in its swinging movement by the abutment of the arms 153 with hub 164 and, as shown in Fig. 6, the right hand arm 163 is held against the hub by the pressure of drive spring 149. The spring 149, as shown by full lines in Fig. 6, is completely stressed and in readiness to move lever 88 to the right as soon as latch 142releases the latter. On release of the latch, the spring will expand and drive lever 88 rapidly to the right into the position shown by dotted lines. The lever 152 is held against movement by the spring due to the lever 160 and this in turn is held against movement by the abutment of one of the arms 163 with hub 164. The reaction of the spring on levers 152 and 160 during the driving of lever 88 to the right, is such as to tend to move lever 152 in a counterclockwise direction and lever 160 in a clock wise direction and such movement is resisted by the abutment of arm 163 with hub 164.

For the purpose of stressing spring 149 and positioning itso as to again act to drive lever 88 back from the dotted line to the full line position shown in Fig. 6, the following mechanism is employed. To the rear end of shaft 161 is fixed the hub 165 of a lever 166 (Fig. 5). This lever near each end is offset rearwardly so that its ends lie in back of the piston rods 67 and each such end is connected by a link 167 to a piece 168, which loosely encompasses the adjacent piston rod. Below each slide piece 168 is a spring 169, which encompasses the piston rod and rests upon v lug 116 in back of sleeve 124. Assuming that lever 88 and drive spring 149 occupy the position shown by dotted lines in Fig. 6, as the right hand piston rod 67 (Fig. 6) moves upwardly, the spring 169 thereon will eventually engage the overlying slide piece 168 and move it upwardly, thereby rocking lever 166 in a counterclockwise direction. Such movement of lever 166 will, throu h lever 160 move lever 152 in a clockwise irection, thereby compressing spring 149. The rod 150 slides in eye 153 to permit this action. The stressing of spring 149 by uprod continues until the left hand arm 163 of lever 160 engages hub 164. Thereafter,

any additional movement of the piston rod,

necessary to cause abutment 69 to engage stop screw 52, simply compresses spring 169.

i The latter does not yield, at least materially,

up to the time when arm 163 engages hub 164.

The stop, provided by the engagement of the two last named elements, is necessary because the point of pivotal connection of lever 152 to rod 150 crosses the line of centers which connects stud 154 to the center of oscillation of eye 153. This crossing of said line of centers occurs near the end of the operation of stressing spring 149 and as a result, the direction in which spring 149 acts on eye 153 is changed. The spring then tends to move valve lever 88 to the left but is restrained for the moment from so doing by the right hand latch 141. The springalso tends to move lever 152 still further in a clockwise direction but is restrained by the engagement of the left hand arm 163 with hub 164. As soon as the right hand latch 141 is released, spring 149 will expand and drive lever 88 with great rapidity back into its left hand posltion, in which it is immediately held by the left hand latch 142. On an ensuing upward movement of the left hand piston rod 67, the lever 166 will be rocked in a clockwise direction which will result in a counter-clockwise movement of lever 152 whereby spring 149 means will be found in my copending application, above referred to. This register will serve to cover the opening 170 shown in Fig. 5 and will be suitably supported from member 162 by means shown in part at 171.

The operation of the apparatus will now be described, assuming that the parts occupy the relative positions shown in Figs. 3 and 6. That is, the left hand cylinder 20 is filled with liquid to the level of its piston 58 and such piston has been moved almost to the upper end of its stroke. The other piston 58 is at the lower end of its cylinder and that cylinder has been emptied. Valve 83 now connects the left hand cylinder to supply pipe 74 and the right hand cylinder to discharge plpe 75. On continued actuation of pump 110, liquid will raise the left hand piston therein until its stop 69 abuts the overlying stop 52. This final raising movement of the left hand piston will compress both springs 123 until sleeves 124 abut nuts 122. Also, lug 118 will raise the left hand latch 142, releasing lever 88 at the instant when piston 58 reaches the upper end of its stroke and the stressing of. springs 123 has been completed. Lever 88 will be moved to the right by spring 149 and valve 83 turned to connect the left hand cylinder 20 to discharge passage 75 and the right hand rocking levers 166, 160 and 152 and causing the valve spring 149 to be compressed between members 151 and 153. When the left hand piston has completed its discharge stroke and come into abutment with member 21, the right hand piston will not have yet reached the end of its upstroke. Pumping being continued, the right hand piston is forced to rise until its abutment 69 engages the overlying abutment 52. Meanwhile. since the left hand piston cannot move further in a downward direction, the springs 123 are compressed. Near the end of the upstroke of the right hand piston, the left hand lug 118 engages the overlying abutment 148 and lifts the same far enough to release lever 88 from latch 142. This release occurs simultaneously with the engagement of the abutment 69 on the right hand piston with the overlying abutment 52. On release of lever 88, it is driven by the expansion of spring 149 into its left hand position and thereby valve 83 is moved to connect the right hand cylinder to discharge passage 75 and the left hand cylinder to supply passage 74. The right hand piston is then moved by the expansion of springs 123 and started on its discharge stroke as described and the left hand piston immediately start upwardly and continues the downward movement of the right hand piston which was initiated by springs 123. There is no interruption in the downward movement of either piston but there is a noticeable sharp kick in the initial movement of each piston, due to the spring impulse which starts it rapidly in motion and imparts momentum to the column of liquid below it to accelerate the discharge. The left hand cylinder is filled and, at the end of the upstroke of the left hand piston, the valve 83 will be reversed in a manner similar to that described.

The described action continues as long as pumping continues, each cylinder alternately filling and discharging and each cylinder discharging while the other is filling and vice versa. The result is the delivery of a pracfrom discharge by gravity flow alone. For

example, from 12 to 14 gallons per minute can be dispensed with the apparatus and this speed is made possible through the automatic shifting of the valve and the arrangement, whereby liquid is forced out from one cylinder as rapidly as it is forced into the other cylinder. This offers a distinct improvementtheir discharge stroke with a spring impulse,

as is preferred, this contributes materially to speedy discharge of the liquid, especially under unfavorable conditions as wherethe delivery hose is bent into a crook and forms a liquid trap.

Referring now to the stopping of the apparatus, except for the arrangement whereby each piston has a dwell at the end of its discharge stroke, it would be diflicult for the operator to stop pumping so that the pistons would come to rest exactly at the end of such strokes. Therefore, the dwell arrangement has an advantage in that it enables the operator, without much trouble, to stop pumping at the proper time. That is, the operator can stop pumping at any time during the interval after the abutment of one-piston with member 21' and before the abutment of the member 69 on the other piston with stop 52. This, however, is not necessary, except to secure speedy delivery of the last gallon, because the arran emen't is such as to permit the last gallon or, if desired, the last part of the last gallon to be delivered by gravity flow. Suppose, for example, that the customer has had nine of the desired ten gallons delivered from the apparatus when the parts are positioned as shown in Fig. 3, the'operator can stop pumping at any time during the rising movement of the right hand piston, and the last gallon will drain from the left hand cylinder by gravity flow, due to the provision of the air vents in the piston. Generally speaking, the customer desires a slower delivery of the last gallon in order to avoid overflowing his tank which maiy then be nearly full. However, if speed is esired, the operator can readily gauge his pumping so that, in the example mentioned,-

the right hand piston will stop short of, but close to, the stop screw 52, thereby forcibly expelling all of the last gallon.

From the foregoing, it will be seen thatv there will normally be some air in one of the cylinders beneath its piston. Such air is expelled through the valve-controlled vents in the piston, when the pump 110 is again operated. Assume for example, that the apparatus stopped with the parts positioned as in Fig. 3, the lefthand cylinder will be drained of liquid and the space below its piston will become filled with air. dropped to the base 21 of the cylinder open The float 66 will have ing the three vents 64:. When pumping is again commenced, the air will be rapidly driven out through these large vents because they are unobstructed by the float. The latter rises with the liquid, leaving the vents open until the liquid reaches the piston 58 and passes into the recess 63 and grooves 70.

These vent valves function, for the most part,

only during the first and last of a succession of cycles of operation. That is, they permit the air to be driven out of the cylinders on starting the pump and they vent the cylinders to permit drainage of the last gallon or part thereof. They may or may not function in intermediate cycles of operation according to whether the pistons dwell in their lower position or not. As illustrated, each-piston dwells in its lower position and its vent valve will open so that all the liquid, including that in the grooves 70, the spaces'between the coils of the spring 57 and that around float 66, is delivered. This arrangement is preferre'dmot only because it enables thespring impulse on the pistons, but because it tends toward the deliveries of uniform quantities of liquid from the cylinders under all conditions. That is, since one piston must drain at least in part by gravity flow, at the end of the last of a series of successive operations,- it has been arranged to have. each piston dwell during intermediate operations of the series. In this way, the float o erated valve 66 will open at the end of each own-stroke of the piston whether the contents are forcibly expelled or pass out by gravity flow. The customer then gets all the liquid pumped into the cylinder including that in said grooves and spaces.

The apparatus is nevertheless workable in commercially satisfactory form even if the dwell of the pistons at the end of their discharge strokes is eliminated and with it the spring impulse, although both these features of the series of unit quantities dispensed.-

Therefore, there would under such conditions be a difference in measurement depending on whether liquid is forced out by the pistons or flows out by gravity. It is therefore important that the total volume of all the spaces in each piston, which are located above the level of the flat bottom face thereof and into which liquid can enter, be kept down to as low a figure as possible. If the grooves '70 *were omitted, a reduction in said volume could be effected but there would then be a possibility of trapping some air below. the piston and more than offset that due to the small volume of these grooves. As hereinbefore set forth,

the volume of these grooves is exceedingly small and the discrepancy which may under certain conditions occasionally be caused by them is not appreciable, being well within the tolerances permitted by the/underwriters. Therefore, since the grooveshave a real useful purpose in avoiding the trapping of air beneath the pistons and facilitating the expulsion of'air from the cylinders, they are thought important and are preferably employed.

The invention has been disclosed herein, in an embodiment at present preferred, for illustrative purposes, but the scope of the invention is defined by the appended claims rather than by the foregoing description.

What Lclaim is:

L. In a liquid dispensing apparatus, a pair of measuring cylinders, a piston in each cylinder, a piston rod fixed to each piston and extending outside its cylinder, a pulley rotatably mounted at a point outside said cylinders, a flexible member trained around the pulley and having its ends connected one to each piston rod at points outside said cylinder,.whereby when one piston is moved in one direction the other will be forced to move in an opposite direction, means for supplying liquid alternately to one end of each cylinder and for discharging liquid from such end of one cylinder while the other is being filled, and a pair of shoes mounted in said pulley for adjustment in a general direction toward and away from the axis thereof and each adapted during the reciprocation of said pistons to engage said flexible member.

2. In a' liquid dispensing apparatus, a pair of measuring cylinders, a piston in each cylinder, a piston rod fixed to each pistonand extending outside its cylinder, a pulley rotatably mounted at a point outside said cylinders, a flexible member trained around the pulley and having its ends connected one to each piston rod at points outside said cylinder, whereby when one piston is moved in one d rection the other will be forced to move in an opposite direction, means for supplying liquid alternately to one end of each cylinder and for discharging liquid from such end of one cylinder while the other is being filled, and a pair of shoes mounted in said pulley for adjustment the one independently of the other in a general direction toward and away from the axis thereof and each adapted during the reciprocation of said pistons to engage said flexible member.

3. In a liquid dispensing apparatus, a pair of measuring cylinders, a piston in each cylinder, a piston rod fixed to each piston and extending outside its cylinder, a pulley rotatably mounted at a point outside said cyl-' inders, a flexible member trained around the pulley and having its ends connected one to each piston rod at points outside said cylinder, whereby when one piston is moved in one direction the other will be forced to move in an opposite direction, means for supplying liquid alternately to one'end of each cylinder and for discharging liquid from such end of one cylinder while the other is being filled, a pair of shoes mounted in said pulley for adjustment in a general direction toward and away from the axis thereof and each adapted during the reciprocation of said pistons to engage said flexible member, and means for positively locking said shoes in various positions of adjustment. 7

4. In a liquid dispensing apparatus, a pair of measuring cylinders, a piston in each cylinder, a piston rod fixed to each piston and extending outside its cylinder, a pulley rotatably mounted at a point outside said cylinders, a flexible member trained around the pulley and having its ends connected one to each piston rod at points outside said cylinder, whereby when one piston is moved in one directionthe other will be forced to move in an opposite direction, .means for supplying liquid alternately to one end of each cylinder and for discharging liquid from such end of one cylinder while the other is being filled, said member at a point substantially midway between its ends being fixed to said pulley, and a pair of shoes mounted in said pulley for adjustment in a general direction toward and away from the axis thereof and adapted during the reciprocation of said pistons to engage said flexible member on opposite sides of the point at which said member is fixed to said pulley.

5. In a liquid dispensing apparatus, a pair of measuring cylinders, a piston in each cylinder, a piston rod fixed to each piston and extending outside its cylinder, a pulley vrotatably mounted at a point outside said cylinders, a flexible member trained around the pulley and having its ends connected one to each piston rod at points outside said cylinder, whereby when one piston is moved in one direction the other will be forced to move in an opposite direction, means for supplying liquid alternately to one end of each cylinder and for discharging liquid from such end of one cylinder while the other i is being filled, said member being fixed at a point substantially midway between its ends to said pulley, and a pair of shoes mounted signature.

JOHN B. DAVIS. 

